// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/filters/vp8_bool_decoder.h"

#include <stddef.h>
#include <stdint.h>

#include <limits>

#include "base/macros.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace media {

const static size_t NUM_BITS_TO_TEST = 100;

namespace {

    // 100 zeros with probability of 0x80.
    const uint8_t kDataZerosAndEvenProbabilities[] = {
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00
    };

    // 100 ones with probability of 0x80.
    const uint8_t kDataOnesAndEvenProbabilities[] = {
        0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xf0, 0x20
    };

    // [0, 1, 0, 1, ..., 1] with probability [0, 1, 2, 3, ..., 99].
    const uint8_t kDataParitiesAndIncreasingProbabilities[] = {
        0x00, 0x02, 0x08, 0x31, 0x8e, 0xca, 0xab, 0xe2, 0xc8, 0x31, 0x12,
        0xb3, 0x2c, 0x19, 0x90, 0xc6, 0x6a, 0xeb, 0x17, 0x52, 0x30
    };

} // namespace

class Vp8BoolDecoderTest : public ::testing::Test {
public:
    Vp8BoolDecoderTest() { }

protected:
    // Fixture member, the bool decoder to be tested.
    Vp8BoolDecoder bd_;

private:
    DISALLOW_COPY_AND_ASSIGN(Vp8BoolDecoderTest);
};

#define INITIALIZE(data) ASSERT_TRUE(bd_.Initialize(data, sizeof(data)));

TEST_F(Vp8BoolDecoderTest, DecodeBoolsWithZerosAndEvenProbabilities)
{
    INITIALIZE(kDataZerosAndEvenProbabilities);
    ASSERT_EQ(0u, bd_.BitOffset());
    for (size_t i = 0; i < NUM_BITS_TO_TEST; ++i) {
        bool out = true;
        ASSERT_TRUE(bd_.ReadBool(&out, 0x80));
        ASSERT_FALSE(out);
        ASSERT_EQ(i, bd_.BitOffset());
    }
}

TEST_F(Vp8BoolDecoderTest, DecodeLiteralsWithZerosAndEvenProbabilities)
{
    INITIALIZE(kDataZerosAndEvenProbabilities);

    int value = 1;
    ASSERT_TRUE(bd_.ReadLiteral(1, &value));
    ASSERT_EQ(0, value);

    value = 1;
    ASSERT_TRUE(bd_.ReadLiteral(32, &value));
    ASSERT_EQ(0, value);

    value = 1;
    ASSERT_TRUE(bd_.ReadLiteralWithSign(1, &value));
    ASSERT_EQ(0, value);

    value = 1;
    ASSERT_TRUE(bd_.ReadLiteralWithSign(31, &value));
    ASSERT_EQ(0, value);
}

TEST_F(Vp8BoolDecoderTest, DecodeBoolsWithOnesAndEvenProbabilities)
{
    INITIALIZE(kDataOnesAndEvenProbabilities);

    ASSERT_EQ(0u, bd_.BitOffset());
    for (size_t i = 0; i < NUM_BITS_TO_TEST; ++i) {
        bool out = false;
        ASSERT_TRUE(bd_.ReadBool(&out, 0x80));
        ASSERT_TRUE(out);
        ASSERT_EQ(i + 1, bd_.BitOffset());
    }
}

TEST_F(Vp8BoolDecoderTest, DecodeLiteralsWithOnesAndEvenProbabilities)
{
    INITIALIZE(kDataOnesAndEvenProbabilities);

    int value = 0;
    ASSERT_TRUE(bd_.ReadLiteral(1, &value));
    EXPECT_EQ(1, value);

    value = 0;
    ASSERT_TRUE(bd_.ReadLiteral(31, &value));
    EXPECT_EQ(0x7FFFFFFF, value);

    value = 0;
    ASSERT_TRUE(bd_.ReadLiteralWithSign(1, &value));
    EXPECT_EQ(-1, value);

    value = 0;
    ASSERT_TRUE(bd_.ReadLiteralWithSign(31, &value));
    EXPECT_EQ(-0x7FFFFFFF, value);
}

TEST_F(Vp8BoolDecoderTest, DecodeBoolsWithParitiesAndIncreasingProbabilities)
{
    INITIALIZE(kDataParitiesAndIncreasingProbabilities);

    for (size_t i = 0; i < NUM_BITS_TO_TEST; ++i) {
        bool out = !(i & 1);
        ASSERT_LE(i, std::numeric_limits<uint8_t>::max());
        ASSERT_TRUE(bd_.ReadBool(&out, static_cast<uint8_t>(i)));
        EXPECT_EQ(out, !!(i & 1));
    }
}

} // namespace media
